DE102005054574A1 - A receiver and method for receiving a digital radio signal and providing a data stream - Google Patents

Abstract

The invention relates to a receiver (1) for receiving digital radio signals and for providing a data stream, comprising: DOLLAR A - several receiving units (5, 6, 7, 8), each designed to receive a digital radio signal and to become one Demodulate intermediate signal; DOLLAR A - a combining unit (17) to combine the intermediate signals to improve the quality into a resulting combined intermediate signal; DOLLAR A - a switching unit (16) which is connected to the receiving units (5, 6, 7, 8) and which is designed to either in a first operating mode at least one of the intermediate signals of the multiple receiving units (5, 6, 7, 8 ) to select for decoding or to make the intermediate signals of the plurality of receiving units available to the combining unit (17) in a second operating mode to improve the quality of the intermediate signal; DOLLAR A - a channel decoder (13) which is connected to the switching unit (16) and the combining unit (17) to either the intermediate signal selected by the switching unit (16) or the intermediate signal combined by the combining unit (17) into a data stream decode.

Description

was standing of the technique

The The invention relates to a receiver for receiving a digital radio signal and for providing a data stream, in particular a two-receiver system. The invention relates a method for receiving a digital radio signal and for providing a data stream.

Receiver for digital Radio signals, in particular DAB receiver (single-receiver systems) received usually only about a transmission channel (a radio signal) the digital data, with only a certain number from different services, e.g. Radio programs, provided can be. These services form the ensemble and merge into each other transmit the following frame in the radio signal.

at previous DAB receivers it is usually not possible a service, e.g. an audio signal, from an ensemble on a transmission channel select and another service, e.g. one data service, another Ensemble, i. on another transmission channel, at the same time too use.

Farther have conventional DAB receivers at a disturbed transmission channel only insufficient possibilities on, the often high bit error rates in the decoded received signal to reduce so that it e.g. leads to audible interference in the audio signal.

It It is an object of the present invention to provide a receiver for Receiving digital radio signals to provide at least a data stream available On the one hand, it is able to process several data streams from different ones To receive ensembles and continue to receive a diversity reception Improvement of the error rate of the data stream can perform. It is a further object of the present invention to provide a method for operating such a receiver for disposal to deliver.

These Task is performed by the receiver Receive a digital radio signal and provide a Data stream and solved by the corresponding method according to the independent claims.

Further advantageous embodiments of the invention are specified in the dependent claims.

According to one The first aspect of the present invention is a receiver for Receiving digital radio signals and providing a data stream intended. The recipient includes multiple receiving units, each designed to be receive a digital radio signal and an intermediate signal to demodulate. Furthermore, the receiver comprises a combination unit, to the intermediate signals to improve the quality to a resulting combined intermediate signal to combine. Further the recipient includes a Switching unit, which is connected to the receiving units and the is designed to operate in either a first mode of operation at least one of the intermediate signals of the plurality of receiving units for decoding select or in a second mode of operation, the intermediate signals of the plurality To provide receiving units of the combination unit. With help of a Channel decoder, with the switching unit and the combination unit is connected, either the selected intermediate signal or decoded combined intermediate signal to a data stream.

Of the receiver according to the invention makes it possible using the switching unit to take two modes of operation, wherein in the first operating mode at least one data stream corresponding a received radio signal is decoded and where appropriate a second mode of operation two or more intermediate signals, the by the demodulation of the same radio signals or the demodulation of Radio signals with the same content are obtained in a combined Intermediate signal are combined to the quality of the data stream encoded therein to improve. The combination of two intermediate signals via independently received radio signals received, is known as diversity reception, the combination this serves to the reception quality to improve. Due to the switching unit, it becomes possible in a two or more receiver system both one or more of the radio signals to one or more streams to demodulate and decode and on the other hand it is possible through Combination of the intermediate signals obtained from the radio signals the reception quality to improve the respective signal.

According to a preferred embodiment, a control unit for selecting the operating mode may be provided, wherein the control unit is connected to the receiving units to tune the receiving units in the second operating mode to the same radio signal and to tune the receiving units in the first operating mode to different radio signals. In this way, it is possible to simultaneously receive a plurality of data streams included in different radio signals or to set the receiving units to the same radio signal for diversity reception, thereby improving reception to reach.

Preferably Each of the intermediate signals has frames in each of which several Data services in blocks are arranged, wherein the control unit is a detection unit for detecting the temporal position of the blocks to at a time not overlapping Receiving blocks of a plurality of intermediate signals between the first and second operating modes switch. this makes possible to use several data services at the same time and also to improve the quality by combining the multiple intermediate signals.

Around simultaneously two data services from different transmission sources receive and use the diversity reception may continue to be provided that the switching unit is designed to be a first and second Intermediate signal to the channel decoder in the first mode of operation disposal with the control unit in the second operating mode the multiple receiving units alternately for receiving the tunes the first intermediate signal underlying radio signal. To this Way to a two different data streams from different transmission sources and when the data streams are transmitted in blocks that do not overlap in time, a diversity reception can be applied, allowing a signal enhancement and thereby a reduced bit error rate is possible.

According to one preferred embodiment the combiner unit adds the intermediate signals to the combined one To receive intermediate signal. In particular, the intermediate signals before the Adding depends from a respective reception quality of the intermediate signal be weighted with a weighting factor.

According to one preferred embodiment the intermediate signals ensembles with multiple data services, the in blocks be provided within a framework. The switching unit can Furthermore, be designed so that the multiple intermediate signals of a De-interleaver unit available be put. The de-interleaver unit Choose each of the plurality of intermediate signals at least one block and put blocks one after another the channel decoder available. Especially the de-interleaver unit can have a memory unit, overlapping in time blocks caching various intermediate signals and using them another output sequential output to the channel decoder. The channel decoder may be configured to block the blocks different intermediate signals to decode several data streams.

According to one Another aspect of the present invention is a method for Receive a digital radio signal and provide a Data stream provided. The method comprises the steps of Receiving multiple digital radio signals, demodulating the plurality of radio signals each to an intermediate signal and the selecting in a first operating mode at least one of the intermediate signals for decoding or combining the intermediate signals in one second mode of operation to a combined intermediate signal for improvement the quality the intermediate signal and the decoding either of the selected intermediate signal or the combined intermediate signal to a data stream.

The inventive method has the advantage of being able to receive in parallel of several radio signals on the one hand to improve the signal in the sense Diversity reception can be used and on the other hand can be used to provide a user with several different data streams, e.g. an audio stream and other data stream available put.

Preferably In the second operating mode, the same radio signal is received multiple times and receive different radio signals in the first operating mode.

According to one preferred embodiment each of the intermediate signals frames in each of a plurality of data services in blocks are arranged, wherein the temporal position of the blocks of the a plurality of intermediate signals is detected, wherein at a time not overlapping Receive the blocks the plurality of intermediate signals between the first and the second Operating mode is changed to obtain multiple data streams and the quality to improve the intermediate signals.

Preferably have the intermediate signals ensembles with multiple data services on, in blocks be provided within frames, wherein among the several Intermediate signals in each case at least one block is selected and the selected ones blocks be decoded one after the other. In particular, temporally overlapping blocks cached various intermediate signals and the blocks be successively passed on for decoding.

preferred embodiments The invention will be described below with reference to the accompanying drawings explained in more detail. It demonstrate:

1 a block diagram of a first part of a two-receiver system for receiving digital radio signals;

2 a subsequent part of the two-receiver system for obtaining a first and a second data stream;

3 a section of the two-receiver system of 1 and 2 to illustrate the operating conditions that can be set by the rear derailleur;

4 illustrates switching between two ensembles to provide two different services to the user.

In 1 is a block diagram of a DAB receiver 1 with two receiving paths 2 . 3 shown. Such a system is also called a two-receiver system. Each of the reception paths 2 . 3 has an antenna 4 which receives the radio signal in a respective pre-stage 5 is mixed and filtered to demodulate the respective received radio signal to an intermediate frequency. Subsequently, the respective intermediate signals to a respective analog-to-digital converter 6 fed, which samples the signal and this digitized. In a subsequent mixer and filter unit 7 The digitized intermediate signal is mixed into the complex baseband and filtered again and the mixed and filtered digital intermediate signal is fed to an OFDM demodulator 8th in which the mixed and filtered digital intermediate signal is demodulated using FFT (Fast Fourier Transform) and DQPSK demodulation. A first and a second OFDM intermediate signal Z1, Z2 are obtained from the two reception paths 2 . 3 , The demodulation of the received radio signals in OFDM intermediate signals Z1, Z2 is sufficiently known from the prior art and will therefore not be explained further here.

at DAB (EN 300 401) are individual radio programs in so-called Services to ensembles summarized and modulated together. The Ensembles are transmitted on one transmission frequency. A typical DAB on-receiver system can demodulate and decode an ensemble. A user of the DAB receiver chooses out of the ensemble the service he wishes to receive in the Case of an audio service the one he wants to hear. Alternatively or also additionally can other services, e.g. Data services are selected in the same Transfer ensemble become. In many reception areas, however, there is more than one ensemble to receive at different transmission frequencies. The user of the usual DAB receiver chooses it first the desired one Ensemble off and then the wished Service in the selected one Ensemble. Would like to the user of the DAB receiver two Services at the same time, which different ensembles, i.e. are assigned to different transmission frequencies, so this is with a one-receiver system not possible. Out For this reason, a two-receiver system will be described below suggested that the reception of two services from different Ensembles possible.

Farther it is known that diversity improves the reception of a signal can be. This is the same signal from two different antennas receive and the resulting intermediate signals in such a way combination unit mentioned combined. This can be done reduce an error rate in the signal. Combining the signals can be done by, for example, evaluating both signals and the better quality signal is selected while the other one is discarded becomes. Furthermore, the combining by addition or a weighted addition the two signals take place, the weighting factors of the Signal-to-noise ratios depend on the corresponding radio signals or intermediate signals. alternative Diversity reception can also be achieved by receiving different ones Radio signals are realized, which are completely or partially identical Services or programs.

The preliminary stages 5 can each be set to a specific reception frequency by means of a frequency selection signal FW1, FW2, so that the antenna 4 is received at the same reception frequency in the diversity case. If two services are to be received on different ensembles, the first preliminary stages can be used 5 be set to different reception frequencies, namely to the two reception frequencies of the ensembles.

In 2 is a second part of the DAB receiver 1 represented according to the present invention. The OFDM intermediate signals Z1 and Z2 become a switching and combining unit 10 in which, depending on a selected operating mode, either one of the two OFDM intermediate signals Z1, Z2 or both is selected or both intermediate signals Z1, Z2 are combined with one another to form a combined intermediate signal. Subsequently, the combined or selected intermediate signal Z becomes a de-interleaver unit 11 supplied with an additional memory 12 connected is. The deinterleaver 11 serves to recover the original bit order scrambled in a transmitter in a corresponding interleaver and sets the selected or combined intermediate signal Z to a channel decoder 13 available, which decodes the intermediate signal Z and depending on the type of data to be received, this an audio decoder 14 or a data decoder 15 provides an ent speaking audio data stream A or payload D to provide the user for output. The decoded data streams can thus contain any type of information, such. As a video, audio, program, display information or the like.

In 3 is a section of the DAB receiver 1 shown in more detail, the switching and combining unit 10 , the de-interleaver 11 and the memory 13 includes. The switching and combination unit 10 includes a switching unit 16 with switches S1, S2 and a combination unit 17 , Depending on the operating mode, a control unit controls 18 the switching unit 16 so that at least one of the two OFDM intermediate signals Z1, Z2 directly to the de-interleaver 11 (switch S1 is connected to A and S2 to D). In a second operating mode, the control unit controls 18 the switching unit 16 that both OFDM intermediate signals Z1, Z2 to the combiner 17 (switch S1 is connected to B and switch S2 to C). There, both OFDM intermediate signals Z1, Z2 are combined in the manner described above, so as to obtain a signal improvement.

The combined OFDM intermediate signal is sent to the de-interleaver 11 from where it immediately via the switch S3 (switch position F) to the subsequent channel decoder 13 is passed on. If two services are to be received simultaneously on different ensembles, then both OFDM intermediate signals Z1, Z2 are sent to the de-interleaver 11 forwarded without these in the combination unit 17 combined (switch S1 is connected to A and switch S2 to D). The deinterleaver 11 is provided for the case that the two services in the ensembles of the OFDM intermediate signals Z1, Z2 as corresponding blocks in the respective intermediate signal at the same time or temporally overlapping at the de-interleaver 11 arrive. The deinterleaver 11 is with the store 12 connected to time simultaneously arriving incoming blocks to be decoded so that these successively to the channel decoder 13 can be passed on. For example, the de-interleaver 11 when blocks in the intermediate OFDM signals Z1, Z2 arrive simultaneously, one of the blocks in the memory 12 and then to the subsequent channel decoder 13 forward, if the block of the other OFDM intermediate signal completely to the channel decoder 13 has been transmitted. The deinterleaver 11 Depending on the operating mode, it processes one OFDM intermediate signal or the several OFDM intermediate signals, so that the bit order is restored.

The control unit 8th sets the reception frequencies in the preliminary stages 5 depending on the operating mode. While diversity reception the same radio signal through the two different receive paths 2 . 3 should be received, for example, in the first mode of operation different services from different ensembles are simultaneously received by different radio signals. That is, in the first operating mode (receiving one or more services), the control unit stops 18 the preliminary stages 5 on various the various ensembles corresponding radio signals and the Diversity reception provides the control unit 18 the reception frequencies to the same frequency to the same radio signal in both receiving paths 2 . 3 to recieve. The switching device 16 thus has the advantage of providing both in a two-receiver system both a diversity reception, so that the error rate can be reduced in a radio signal, as well as the ability to receive multiple services from different ensembles to receive and provide a user simultaneously.

Since in DAB only the OFDM symbols in the ensemble containing the service to be received need to be decoded, the reception of two different ensembles at different receiving frequencies makes it possible to realize both diversity reception and the two services to the user when the blocks containing the corresponding services in the ensembles are sent offset in time. In 4 two ensembles are shown schematically, the first ensemble sending a first service D1 and the second ensemble sending a second service D2 offset in time. Each ensemble is transmitted in equally long frames with multiple blocks, each frame being initiated by a null symbol, a TFPR symbol, and a FIC symbol that allow the receiver to synchronize to the frame and provide information to the receiver indicating what kind of information is subsequently sent in the data blocks. Since the zero symbol, the TFPR symbol and the FIC symbol occur in each frame and contain identical information, it is possible that they are not evaluated in every frame, but only in every second, in every third, etc. frame must be evaluated , which leads to a sufficiently accurate synchronization and sufficient content information. Thus, it is possible to switch to receiving the radio signal for the respective block for a certain time only for receiving a service, while in the rest of the time the reception path is set to a different frequency. In this case, the reception of several, ie two services allow and simultaneously use the diversity reception. The switching unit 16 is in accordance with the second operating mode geschal tet, so that the two OFDM intermediate signals Z1, Z2 to the combiner 17 be routed to produce the combined intermediate signal. The combined intermediate signal is passed through the de-interleaver 11 directed to the channel decoder. The control unit 18 now uses the frequency selection signals FW1, FW2 to toggle between receiving the first data service D1 in the time window of the first data service D1 and receiving the second data service D2 in the corresponding time window of the second data service D2. Thus, first the symbols 020 to 022 of the first service D1 from the first ensemble are received and decoded by both receiving units, and then the symbols 08 to 010 of the second data service D2.

That is, the control unit 18 uses the frequency signals FW1 and FW2 to set the reception frequency to the reception of the first ensemble in both reception paths 2 . 3 and receives the blocks 020 to 022 for the first data service D1, and then changes the reception frequency to the reception frequency of the second ensemble to receive the blocks 08 to 010 of the second data service D2 with both reception paths. At regular intervals, however, it is necessary to decode the headers of a frame of each ensemble, so that in these cases it is switched back to the first operating mode, and the intermediate signals Z1 and Z2 of both ensembles (the receiving paths are set to different receiving frequencies) the de-interleaver 11 to get redirected. This change may be made on every other, third, etc., frame as necessary to receive the headers of the frames.

The control unit 18 can also receive the intermediate signals Z1 and Z2 and determine their signal quality, for example in the form of a signal-to-noise ratio. The control unit 18 can then switch between the first and second operating modes, depending on the signal quality of the intermediate signals Z1, Z2. Here, a priority control makes sense, wherein each of the services can be provided with a certain priority. In this case, it makes sense to assign a higher priority to an audio data service than to a useful data service, as interruptions in an audio signal are immediately noticeable to the user. The DAB receiver can then use the diversity reception in difficult reception situations, ie in the case of poor signal qualities of the reception signals, ie the reception frequencies of the precursors 5 in both reception paths 2 . 3 set to the same receiving frequency and according to the second operating mode, the OFDM intermediate signals Z1, Z2 the combiner 17 to improve the quality of the received audio signal.

The DAB receiver 1 as he in connection with the 1 to 3 may also be implemented by following the analog-to-digital converters 6 the two reception paths 2 . 3 a memory is provided which successively blocks the respective blocks of the first and the second ensemble to jointly executed mixers and filters 7 as well as a demodulator 8th be supplied, so that the additional circuit complexity can be reduced for the de-interleaver.

Claims (13)

Receiver ( 1 ) for receiving digital radio signals and for providing a data stream, comprising: - a plurality of receiving units ( 5 . 6 . 7 . 8th each configured to receive a digital radio signal and to demodulate it into an intermediate signal; A combination unit ( 17 ) to combine the intermediate signals to improve the quality to a resulting combined intermediate signal; A switching unit ( 16 ) connected to the receiving units ( 5 . 6 . 7 . 8th ) and which is designed in order, either in a first operating mode, to connect at least one of the intermediate signals of the plurality of receiving units ( 5 . 6 . 7 . 8th ) for decoding or in a second operating mode, the intermediate signals of the multiple receiving units of the combining unit ( 17 ) to combine to improve the quality of the intermediate signal; A channel decoder ( 13 ) connected to the switching unit ( 16 ) and the combination unit ( 17 ) is connected to either the switch unit ( 16 ) selected intermediate signal or that of the combination unit ( 17 ) decode combined intermediate signal into a data stream. Receiver according to claim 1, wherein a control unit ( 18 ) is provided for selecting the operating mode, wherein the control unit ( 18 ) with the receiving units ( 5 . 6 . 7 . 8th ) is connected to the receiving units ( 5 . 6 . 7 . 8th ) in the second operating mode to the same radio signal to tune and the receiving units ( 5 . 6 . 7 . 8th ) in the first mode of operation to tune to different radio signals. A receiver according to claim 2, wherein each of said intermediate signals (Z1, Z2) comprises frames in which a plurality of data services are arranged in blocks, said control unit ( 18 ) has a detection unit for detecting the temporal position of the blocks in order to switch between the first and the second operating mode in the case of a non-overlapping receiving of blocks of the plurality of intermediate signals. Receiver according to claim 3, wherein the switching unit ( 16 ) is configured to supply a first and second intermediate signal (Z1, Z2) to the channel decoder ( 13 ) in the first operating mode, the control unit ( 18 ) in the second operating mode, the plurality of receiving units ( 5 . 6 . 7 . 8th ) alternately tunes to receive the radio signal underlying the first intermediate signal and the radio signal underlying the second intermediate signal. Receiver according to one of claims 1 to 4, wherein the combination unit ( 17 ) adds the intermediate signals to obtain the combined intermediate signal. Receiver according to claim 5, wherein the combining unit ( 17 ) is designed to weight the intermediate signals prior to adding, depending on a respective reception quality of the radio signal underlying the intermediate signal with a weighting factor. A receiver according to any one of claims 1 to 6, wherein the intermediate signals comprise ensembles having a plurality of data services provided in blocks within a frame, the switching unit ( 16 ) is further configured to provide the plurality of intermediate signals of a de-interleaver unit ( 11 ) and the de-interleaver unit ( 11 ) is configured to select at least one block from each of the plurality of intermediate signals, and the blocks are successively assigned to the channel decoder ( 12 ) to provide. Receiver ( 1 ) according to claim 6, wherein the de-interleaver unit ( 11 ) has a memory unit for temporarily storing blocks of different intermediate signals which overlap in time, and for sequentially sending them to the channel decoder (11) with the aid of a further switching unit. 13 ), the channel decoder ( 13 ) is configured to decode the blocks of the various intermediate signals into a plurality of data streams. Method for receiving digital radio signals and for providing at least one data stream, with the following steps: - receive of several digital radio signals; - demodulate the several Radio signals each to an intermediate signal; - in one first operating mode, Select at least one of the intermediate signals for decoding, or in one second operating mode Combining the intermediate signals to a combined one Intermediate signal for improving the quality of the intermediate signal; - decode either of the selected Intermediate signal or the combined intermediate signal to a data stream. Method according to claim 9, with the further steps: - by doing second mode of operation, multiple receiving the same radio signal; and - in the first mode of operation receiving different radio signals. The method of claim 10, wherein each of the intermediate signals Frame in which each arranged several data services in blocks are, wherein the temporal position of the blocks of the plurality of intermediate signals is detected, wherein in a temporally non-overlapping receiving the Blocks the a plurality of intermediate signals between the first and second operating modes is changed to obtain multiple data streams and the quality of the intermediate signals to improve. Method according to one of claims 9 to 11, wherein the intermediate signals Ensembles with multiple data services, in blocks within provided by frames, wherein among the plurality of intermediate signals at least one block is selected and the selected blocks in succession be decoded. The method of claim 12, wherein temporally overlapping blocks cached various intermediate signals and the Blocks in succession be passed on for decoding.